A&P Exam 2: Membrane Potential and Cell Organelles Overview

Resting membrane potential (RMP)

Produced by separation of oppositely charged particles across plasma membrane in all cells.

Voltage

Occurs only at membrane surface, with the rest of the cell and extracellular fluid being neutral. Membrane voltages range from -50 to -100 mV in different cells.

K+

Key player in RMP; negatively charged proteins cannot leave, leading to the cytoplasmic side of the cell membrane becoming more negative.

Active Transport

Maintains electrochemical gradients by continuously ejecting Na+ out of the cell and bringing K+ inside, maintaining a steady state.

Nucleus

Organelle that allows substances to pass into and out of the nucleus.

Nucleolus

Dark-staining spherical body within the nucleus involved in ribosomal RNA synthesis.

Chromatin

Uncoiled DNA; condensed chromatin are chromosomes.

Mitochondria

Known as the "power plant" of cells, producing most of the cell's energy molecules (ATP) via aerobic cellular respiration.

Endoplasmic reticulum

Consists of parallel, flattened membranous tubes that synthesize proteins; rough ER has ribosomes on its surface, while smooth ER functions in lipid synthesis.

Golgi apparatus

Stacked and flattened membranous sacs that modify, concentrate, and package proteins and lipids.

Peroxisomes

Membranous sacs containing detoxifying substances that neutralize toxins and play a role in breakdown and synthesis of fatty acids.

Lysosomes

Spherical membranous bags containing digestive enzymes that degrade ingested bacteria, viruses, toxins, and nonfunctional organelles.

Ribosomes

Nonmembranous organelles that are the site of protein synthesis, either free-floating or attached to the endoplasmic reticulum.

Cytoskeleton

Extensive network of microtubules and microfilaments that play a role in the movement of cell components.

Centrioles

Pair of barrel-shaped organelles involved in cell division and the formation of cilia and flagella.